Chabad.org — English translation + Rashi
Torah Temimah points to Zevachim 34b (unit 6; single primary locus per emergency Core plan).
E-Daf.com — Zevachim 34b
HebrewBooks / Shas PDF
English: “And its blood he shall pour out” — this teaches that the residual blood is poured to the base.
Shefichat shirayim at the yesod — after the horn applications, remaining blood is poured at the base of the altar.
Once the required applications to the horns are complete, any residual blood is poured onto the base (yesod) of the altar. This shefichah is an integral part of the service of the outer chatas; omitting it leaves the blood-disposal incomplete.